Topic Test 3 Flashcards
what is the importance of structure (in neuroanatomy)?
tells us a lot about function
- complexity of human cerebrum surface
- size of olfactory bulb (think about purpose, ex. in rats their bulb relatively much larger = better neurons for smell and sense of smell)
Historically we didn’t have brain imaging techniques to rely on - what was used?
dissection (postmortem) and staining (cut into thin slices and stain with chemicals)
*now we can see in vivo!
new technologies (in brain imaging) allow us to see _
living brains (in vivo)
describe the 2 major types of imaging
- Structural (structure of brain)
- Functional (gives additional info where we ssee changes happening while people are thinking/doing things)
*+other techniques and advancements
list the tests used in structural imaging
- computed tomography (CT/CAT) - 70s
- magnetic resonance imaging (MRI) - 80s
list the tests used in functional imaging
- positron emission tomography (PET) - 80s
- functional MRI (fMRI) - 90s
list other techniques and advancements (aside from structural/functional)
- diffusion tensor imaging - 90s
- improving MRIs
describe CT (and give the full name)
computed tomography (CT/CAT)
- digitally reconstructed x-rays (360 degrees to provide “slices” of the object
(cross section in different orientations)
list the pros of CT scans
PROS
- can see bone, brain, organs, etc. (good at picking up differences in tissue)
- great for bleeding and tumors (ex. intercranial hemmorhage)
- quick scan
- lower cost and shorter wait times than MRI
List the cons of CT scans
CONS
- low doses of radiation
- images may not be as detailed as other techniques
describe MRI (and provide full name)
magnetic resonance imaging
- no radiation, just a large magnetic field
- different atoms interact differently within the magnetic field (interprets this and makes a 3D picture)
- build a “map” based on this (can also have slices in any direction)
- stronger magnet = clearer images
how is the strength of the magnet communicated in MRIs?
rated as Tesla units (0.5T-3t+)
- 3T = clearer magnet and higher resolution
*can go higher but usually to 3t
describe the pros of MRIs
- no radiation
- great view of soft tissues (while CT was good at bone structure)
- can highlight different types of tissues (eg. T1 vs T2)
What’s the difference between T1 and T2 MRIs?
T1: enhances the signal of the fatty tissue and suppresses the signal of the water
T2: T2-weighted MRI enhances the signal of the water (ie. can see CSF)
list the cons of MRI
- longer scan times
- can be very noisy
- metal implants may cause issues
- longer wait times and more expensive
- magnet can be dangerous (attracts everything metal, is always on)
MRI provides _ based on specific sequences of the scan
“slices” of images
what brain imaging technique is often used in MS?
MRI is the best way to see lesions
- preferred diagnosis technique (not only diagnosing factor but can help)
- symptoms + imaging and other tests
- can identify previous damage, new inflammation, and even atrophy over time (can see fluid/edema/inflammation around myelin)
describe PET (and provide full name)
- imaging with radioactive tracer
- can be used with CT or MRI
- IV with tracer and compounds used by the body (e.g. glucose)
- measures metabolic activity of the cells of body tissues (highlights active areas when certain areas use more glucose)
- used to diagnoses brain disorders, cancers, etc.
describe what fluorodopa is and how it’s used
- specific tracer that can be used in PET scan (but maybe also MRI?)
- mimics dopa, used as building block to create dopamine
- used to detect damaged or lost dopaminergic neurons
- support the diagnosis and the evaluating progression and treatment
Describe FMRI (and provide full name)
- measure changes in blood flow
- increased blood flow (RED on picture) means increased neural activity, decreased (BLUE)
- no injection required and better resolution than PET
- used to map brains for surgery, diagnose diseases, and provides many research opportunities
describe new technique - diffusion tensor imaging
- visualizes large bundles of axons in the brain
- uses an MRI to compare the diffusion of water that occurs along axons
- direction of traces are represented with different colours
- understand and track the changes in teh structure of the brain with aging/disease
describe the new technique - improving MRIs
- most “new” techniques come in the form of improvements of this technology
- improving scan times (2-3 minutes to seconds)
- improving resolution of images (<3T)
- segmentation of images (could be helpful in identifying/monitoring disease)
- measuring different tings (fluid levels, tissue stiffness, etc.)
while we have amazing tech adcances and ongoing breakthroughs in imaging, moving these techniques into _ takes time
clinical practice
name the anatomical planes
*three major planes, all 90 degrees to each other
- sagittal (midsaggital split down the middle)
- frontal (coronal)
- transverse (horizontal)
list the anatomical terms
- dorsal (superior at brain/towards back at SC)
- caudal (posterior)
- rostral (anterior)
- ventral (inferior at brain and anterior at SC)
how is the nervous system divided in gross organization of the body?
- central nervous system (cns/brain and SC)
- peripheral nervous system (pns)
describe the spinal cord
- conduit of information (brain-body)
- spinal nerves
- dorsal roots - sensory (afferent)
- ventral roots - motor (efferent)
*still lots of processing happening here
define dorsal root ganglia
clusters of neuronal cell bodies outside the spinal cord that contain somatic sensory axons
describe the peripheral nervous system
- nervous system outside the brain and spinal cord
somatic PNS: innervates skin, joints, muscles
*dorsal root ganglia: clusters of neuronal cel bodies outside the spinal cord that contain somatic sensory axons - visceral PNS: innervates internal organs, blood vessels, glands
where are soma of sensory nerves located?
outside of spinal cord
differentiate afferent and efferent axons
- afferent (“carry to”): carry information toward the CNS (ie. sensory)
*affect = feeling - efferent (“carry from”): carry information away from CNS (ie. motor)
*effect = affecting other things in environment
describe the terminology used to describe the collection of neuronal bodies (somas)
- gray matter: neuronal bodies in the CNS
- nucleus: mass of neuronal bodies in the CNS
- ganglion: collection of neuronal bodies in the PNS
define gray matter
neuronal bodies in the CNS
define nucleus
mass of neuronal bodies in the CNS
define ganglion
ollection of neuronal bodies in the PNS
describe the terminology used to describe the collection of axons
- White matter: collection of axons in the CNS
- Nerve: bundle of axons in the PNS
- Tract: collection of axons with a common origin and destination in the CNS
define white matter
collection of axons in the CNS
define nerve
bundle of axons in the PNS
define tract
collection of axons with a common origin and destination in the CNS
compare the location of grey/white matter in spinal cord vs brain
spinal cord has grey matter on centre and white on outside, opposite for brain
describe CSF
*cerebrospinal fluid
- produced by choroid plexus found within the brain
- circulates throughout the CNS
- absorbed into venous system
Functions:
- protection
- buoyancy
- excrete waste products
- exocrine medium
describe the ventricles
- filled with CSF
- 4 of them: 1st and 2nd are lateral ventricles, third is lower, and 4th lower (between brainstem and the cerebellum) separated by an aqueduct
describe the lateral ventricles
largest cavities
- also called 1st and 2nd ventricles
describe the 3rd and 4th ventricles
- connected via cerebral aqueduct
- 3rd ventricle is between 2 halves of diencephalon
- 4th ventricle posterior to pons & medulla, but anterior to the cerebellum (continues with central canal of spinal cord)
how is the brain generally divided?
forebrain/midbrain/hindbrain
list the structures in the forebrain
telencephalon (cerebrum)
diencephalon
list the structures in the hindbrain
- cerebellum, pons, medulla oblongata
describe the telencephalon/cerebrum
largest part of human brain (2 cerebral hemispheres)
- cerebral cortex (outer layer)
- white matter (3 groupings)
- basal ganglia
- amygdala
- hippocampus
*responsible for a variety of tasks
what tasts is telencephalon/cerebrum responsible for?
- higher order thinking/reasoning
- analyse sensory input and command motor output
- memory and emotion
describe the 3 major white matter systems
axons extend from developing forebrain to other parts of nervous system
- cortical white matter (axons of the cerebral cortex)
- corpus callosum (bridge between left/right hemispheres)
- internal capsule (links brain to brain stem - axons coming together and coming down to brain stem)
describe the diencephalon
- a little deeper inside
Thalamus - gateway to cerebral cortex
- (infofrom eye/ear/skin etc. goes through thalamus) via the internal capsule
Hypothalamus - roles in a variety of autonomic functions and hormone release
anytime we have a synapse, there is a reason for that synapse. Why?
- if we wanter to send info straight to a destination, we wouldn’t have a synapse
- thalamus does a lot of manipulation of info, key in up/downregulating different senses
describe the midbrain
- contains ascending/descending pathways between cortex, brain stem, and spinal cord (note cerebral aqueduct in centre)
- tectum & tegmentum
*still plays an important part in voluntary control of movement
describe the tectum
- in midbrain
- receive sensory information from eye/ear
describe the tegmentum
- in midbrain
- contains the substantia nigra (black substance) and red nucleus which help to control voluntary movement (these are 2 groupings of neurons)
name the 3 important structures in the hindbrain
cerebellum, pons, medulla oblongata
describe the cerebellum
*hindbrain
- most posterior
- movement control centre (specifically fine movement control)
describe the pons
*hindbrain
- most superior/rostral, also anterior
- switchboard connecting cerebellum and cerebral cortex
describe the medulla oblongata
- most inferior/caudal
- autonomic processes (breathing, blood pressure, etc.) *the lower you go, the more automated you get
- also, relays information to thalamus
*big point of axon crossover
4th ventricle arises from the _
cerebral aqueduct
what are the meddulary pyramids
the point of decussation/axon crossover
describe the spinal cord in terms of matter and location
- white matter in outer layer (superficial)
- gray matter inside (deep)
- spinal canal - extension of 4th ventricle (CSF needs to flow through)
Which structure is this: most superior structure in hindbrain and anterior to 4th ventricle. Switchboard connecting cerebellum and cerebral cortex
pons
What structure is this? Most inferior structure of hindbrain and lays anterior to 4th ventricle. Involved in autonomic processes and relaying information to thalamus
medulla
*also contains medulla pyramids which allow axons to cross over (decussation).
which structure is the most posterior structure and is the movement control centre?
cerebellum
what structures maximize surface area in the cerebral cortex?
gyri (bumbs), sulco (grooves), and fissures (deep grooves)
describe the central sulcus
*splitting in frontal plane
- separates pre and postcentral gyrus
- precentral gyrus - voluntary movement centre (lasy sendout of motor is here)
- postcentral gyrus - somatic sensation (first info is coming in here)
describe the lateral fissure
- located superior to superior temporal gyrus
- superior temporal gyrus: hearing
what are the 4 primary lobes in the cerebral cortex?
- frontal
- parietal (central sulcus)
- temporal (lateral fissure)
- occipital
list the areas of the frontal lobe
- prefrontal cortex
- premotor & supplementary motor area (Broddman’s ^)
- primary motor cortex (M1/broddman’s 4)
describe the prefrontal cortex
- executive function - higher cognitive processes for planning and organizing thoughts, speech, and behavious
- attention: can directly or inderectly influence movement
- personality and social behaviour
*higher-order thinking
what maps the brain into different sensory/motor and association areas?
Broddman’s map
what case study helps us understand the prefrontal cortex better?
finneas gage
- metal pole went through prefrontal cortex
- alive but personality different, has issues controlling emotions, more childish, change in social behaviour, issues with social attention
describe the premotor & supplementary motor area
*b’s 6
- preparation of the body for movement
(info goes from prefrontal>premotor>primary motor cortex)
describe the primary motor cortex
*brodmann’s 4
- precentral gyrus
- generates neural impulses for movement
- somatotopic motor map
(info can be sent out down spinal cord out to muscles to execute the action)
describe the somatotopic motor map
- rough overview of motor organization
- splitting down area 4
- the larger something is, the more neurons we have devoted to the brain (ex. hand is larger because we need a lot of motor control and fine motor control, legs are smaller cause more gross motor pattern)
if we put an electrode on an area on the somatotopic motor map, what can we expect?
- fire signals, doesn’t necessarily mean we can control that area but would expect to have some activation of that area
*not 1-1 relationship, not mapped perfectly in cortex
but gives good picture
list the areas of the parietal lobe
- somatosensory cortex (s1 or b’s 1-3)
- posterior parietal cortex
describe the somatosensory cortex
- postcentral gyrus
- primary area for processing somatic sensations
- somatotopic sensory map
describe the posterior parietal cortex
- integrating sensory information
- object recognition, spatial relationships, etc.
- contributes to planning and organizing action
ex. reach into bag and can identify an object based on tactile sensation
describe what happens in the occipital lobe
- visual cortex, processes visual information
*first point of processing starts back here and gets sent to other places
describe what happens in the temporal lobe & what cortexs are included
- auditory cortex (processes auditory info)
- inferotemporal cortex (visual processing and object recognition)
describe object recognition
visual info passed from visual cortex to inferotemporal cortex
- quickly and easily identify objects
- don’t fully understand yet (how humans do this so well)
- artificial tech (face recognition, took a long time to develop)
the thalamus is part of the
diancephalon
describe the location/structure and main function of the thalamus
- sagittal view = duck’s head (hypothalamus is beak)
- 3rd ventricle is between 2 halves
*link between sensory info and cerebrum
describe the function of the thalamus in more detail
- previously thought to just be relay - more than that!
- processes (excites/inhibits) and directs to specific areas (air traffic controller)
- highly integrated with cerebellum and basal ganglia with cortex
- axons travel through internal capsule
what real-world comparison similar to the thalamus was brought up in class
air traffic controller
- thalamus is getting a bunch of sensory info coming up, it’s job is to direct that to specific areas and understand where it needs to go
- or celebrity agent (choosing which jobs are worth taking a look at)
from a coronal view of the thalamus, we can see that _
it has left and right sides
*can divide it up further, there are a lot of nuclei in the thalamus (groupings of neurons that do similar things)
The thalamus is divided into _
seperate nuclei that project to different areas in the cortex
name the nucli the thalamus divides into
- ventral posterior (VP) nucleus
- ventral lateral (VL) nucleus
describe the ventral posterior nucleus
- projects to the postcentral gyrus
*sends sensory info up to postcentral gyrus
describe the ventral lateral nucleus
- projects to precentral gyrus
- receives input from basal ganglia (bit of a loop, helps finetune some signals)
primary motor cortex, where the precentral gyrus is, should be sending info out for motor commandssending motor info
define the basal ganglia
group of subcortical nuclei which supports the selection and initiation of movements, while preventing unwanted movements (among other things)
the basal ganglia involves nuclei in the _
telencephalon, diencephalon (forebrain) and midbrain
*group of neurons in the CNS
*work together to help select and initiate movements, prevent unwanted ones
why is the basal ganglia important in parkinson’s?
if there is damage here, makes it difficult to initiate movements and to select the right movements
when deciding what we need to do based on environment, the cortex goes to _, which goes to _
premotor
- beforesent out, will loop down to basal ganglia as consultation
- thalamus
the basal ganglia has 4 main nuclei, name them
striatum, globus pallidus, subthalamic nucleus, substantia nigra
describe the striatum
- horn-like thing
- includes caudate nucleus and putamen
- where info is coming first, then globus pallidus
describe the globus pallidus
- internal & external segment
- gets sent out to thalamus but along with it gets input from the subthalamic nucleus
describe the subthalamic nucleus
- helps regulate movement
- below the thalamus
describe the substantia nigra
- helps regulate movement - dopaminergic neurons
- degeneration in parkinson’s disease
what are the 3 kinds of white matter?
- cortical white matter
- left internal capsule
- corpus callosum
describe the pons
- ventral to 4th ventricle in the hindbrain
- relays cortical info to cerebellum
- pontine reticular info
(important for respiration, tast and sleep: as well as postural control.) - many ascending and descending tracts carrying sensory and motor information (superhighway)
describe the cerebellum
- “little brain”
- most dorsal aspect of the hindbrain
- has folia (like gyri) and lobules (like lobes)
- vermis separates left and right hemisphere (like corpus callosum)
- deep cerebellar nuclei relay info out
*finetuning things like with cortex/basal ganglia
what are purkinje cells
main cells we have in the cerebellum
- massive network of dendrites
- receive a ton of info, send it out in one axon
- a lot of processing, coordinate and finetune this
*loss + damage of these = loss in coordination (ataxia)
damage to the cerebellum leads to _
uncoordinated movements (ataxia)
- ex. finger to nose test, lacks finetuning/ a little bit off
what case study describes what happens in cerebellum? What’s a real life example of how we use this knowledge?
- someone with alcoholic cerebellar degenerative problems
- degeneration in cerebellum after 30 yrs of korean hard liquor
- normal cognitive and mental state, but ataxic movement
*why we do sobriety tests, alcohol stops cerebellum from doing it’s job
list the components of the medulla
- medullary pyramids
- medial lemniscus
- vestibular nucleus
- dorsal column nuclei
describe the medulla
most caudal portion of hindbrain
- medullary pyramids, medial lemniscus, vestibular nucleus
describe the medullary pyramids
- bundles of motor axons
- primary point of motor decussation (crossover, motor info doing down, sensory up, axons cross over in pyramids)
describe the medial lemniscus
- bundles of sensory axons
- coming from periphery/tactile
- going through medial lemniscus (bundles of sensory axons)
describe the vestibular nucleus
integrates information necessary for balance
*info being integrated from sensors in ears
describe the dorsal column nuclei
- primary point of sensory decussation
- joins up with medial lemniscus to create the dorsal column-medial lemniscus (DCML) pathway
the spinal cord has _ vertrebrae and _ spinal nerves
33 vertebrae, 31 spinal nerves
*not 1-1!
- have 7 cervical vertebrae with nerves on either side =8
- throughout the thoracic, lumbar, sacral, pretty easy 1-1
- in the coccyx where we are fusing a lot of these together, we only have 1 nerve
what 5 vertebrae can we landmark?
c2- first bony point
c7 - most prominent
t8 - bottom of sternum
t12 - bottom of ribs
l4/5 - top of iliac crests
*very commonfor nerve/disk issues
describe the spinal cord
spinal nerve splits into 2 roots (dorsal - sensory, ventral = motor)
- grey matter on inside
- gray matter (dorsal, ventral, and lateral horns
- white matter, axons running up and down (dorsal, ventral and lateral columns
the spinal cord has ascending sensory pathways and descending motor pathways, describe the ascending
ascending sensory
- dorsal column (touch, proprioception)
- spinothalamic tract (pain, temp)
the spinal cord has ascending sensory pathways and descending motor pathways, describe the descending
descending motor
- lateral motor pathways (commands for voluntary movements)
- ventromedial motor pathways (posture and reflex movements)
